save time and cost with modification codes for space grade … · 2019-06-27 · micro-d special...

Micr

o-D

Spec

ial A

pps a

nd

MOD

s

K

Special Screening Only Special Screening Plus Outgassing Processing

NASA Screening Level

Interfacial Seal is

Installed

Interfacial Seal is

Deleted

48 Hour Oven Bake

175° C.

Thermal Vacuum

Outgassing24 hrs. 125° C.

Level 1 Highest Reliability

Mod Code 429B

Mod Code 429F

Mod Code 429J

Mod Code 429C

Level 2 High Reliability

Mod Code 429

Mod Code 429D

Mod Code 429K

Mod Code 429A

Level 3 Standard Reliability

(Use standard part number)

Mod Code 432

Mod Code 186

Mod Code 186M

Save Time and Cost with Modification Codes for Space Grade Micro-D’sMicro-D TwistPin connectors are a good choice for all types of orbital and deep space projects. Glenair Modification Codes provide special processing for Micro-D’s to meet NASA requirements without the need for a customer

‘Statement of Work’ or ‘Specification Control Drawing’. This section explains Glenair Modification Code ordering, and provides valuable information on outgassing and other space flight topics.

How To Order Space Grade Micro-D’s

Step 1: Find a Standard Micro-D Part NumberElectroless nickel plated shells and Tefzel® wire are preferred for space flight. Cadmium plating is prohibited.

Step 2: Select a NASA Screening LevelThe term “Screening Level” refers to the final inspection procedure and does not include outgassing. Level 1 for mission-critical highest reliability Level 2 for high reliabilityLevel 3 for standard reliability

Step 3: Outgassing ProcessingA detailed explanation of outgassing is on the following pages. The interfacial seal on Micro-D receptacles does not meet NASA outgassing requirements unless it is baked or thermal vacuum outgassed. Some customers specify deleting the seal, some opt for a bakeout, and some customers specify thermal vacuum outgassing. Both bakeout and thermal vacuum outgas processes incur additional cost.

Step 4: Select Appropriate Modification Code. Match the desired level of screening, outgassing or a combination of both. Select from the table below to choose the right modification code. Add the modification code to the connector part number. Example: MWDM2L-37P-6J5-18L-429C

Micro-D Modification Codes for Space Grade Applications

Detail of the Atmospheric Infrared Sounder Instrument (AIRS) with Glenair Micro-D Cables and ConnectorsPhoto courtesy JPL

Six things you should know about Micro-D connectors for space flight

1Outgassing : What is outgassing, why is it important, and how

does it affect connector selection? Is special processing required to meet outgassing requirements?

2Screening : What is NASA screening and what level of

screening is required?

3Magnetic permeability : Are nonmagnetic connectors required?

4Cryogenic exposure : Are Micro-D connectors suitable for -200° C.

exposure?

5Materials : Micro-D connectors offer a variety of materials and

plating finishes. Which ones are recommended for space flight?

6Wire Corrosion : M22759/33 irradiated Tefzel® wire is preferred

for space applications. What about corrosion problems caused by this wire?

Rev. 06.24.19

© 2013 Glenair, Inc. High Performance Micro-D Connectors and Cables U.S. CAGE Code 06324 Printed in U.S.A.

GLENAIR, INC. • 1211 AIR WAY • GLENDALE, CA 91201-2497 • 818-247-6000 • FAX 818-500-9912www.glenair.com K-7 E-Mail: [email protected]

Micro-D

Special Apps and M

ODs

K

Outgassing for Space-Grade Applications

1 Outgassing : What is outgassing and how does it affect connector

selection? Is special processing required to meet outgassing requirements?

What is outgassing?Plastic and rubber materials give off gaseous molecules. For example, the smell inside a new car is caused by polymer outgassing. Heat and vacuum increase the rate of diffusion. In a spacecraft the gases coming off polymers can contaminate optical surfaces and instruments. The result is degraded performance.

How is outgassing measured?The space industry has adopted a standardized test procedure, ASTM E 595, to evaluate out-gassing properties of polymers. Small samples of material are heated to 125° C. at a vacuum of 5 X 10-5 torr for 24 hours. Then the sample is weighed to calculate the Total Mass Loss (TML). The TML cannot exceed 1.00% of the total initial mass. During the test, outgassed matter condenses on a cooled collector plate. The quantity of outgassed matter is caluclated to determine the Collected Volatile Condensable Material (CVCM). The CVCM cannot exceed 0.10% of the original specimen mass.

Table 1: Outgassing Properties of Materials Used in Conjunction with Micro-D Connectors

Component MaterialBrand Name

% Total Mass Loss (TML)

% Collected Volatile Con-densable Material (CVCM)

Test Report

Thermoplastic Insulators and PCB Trays

Liquid Crystal Polymer

Vectra® C-130

0.03 0.00NASA Test

#GSC17478

Potting Compound EpoxyHysol C9-

42150.48 0.01 Glenair Test

Interfacial Seal “as received” Fluorosilicone (none) 0.99 0.13 Glenair Test

Interfacial Seal with Oven Bakeout 8 hrs. 400° F.

Fluorosilicone (none) 0.03 0.01 Glenair Test

Interfacial Seal with Thermal Vacuum Bakeout24 hrs. 125° C.

Fluorosilicone (none) 0.08 0.02 Glenair Test

Wire Tefzel® Tefzel® 0.22 0.01NASA Test

#GSC19998

MIL-DTL-83513 specifies that Micro-D connectors must meet outgassing requirements, but the interfacial seal exceeds the limit. How can this be?The mil spec allows the TML and CVCM to be calculated based on the total mass of the nonmetallic components. The interfacial seal can exceed outgassing limits as long as the insulator and potting compound are well below maximum outgassing limits.

Is special outgassing necessary?It depends on the customer. Some programs specify that all connectors be oven baked or thermal vacuum outgassed. For example, NASA GSFC programs typically require that the interfacial seals are deleted,along with level I screening and thermal vacuum outgassing processing.

Why pay extra for bakeout or thermal vacuum outgassing?If the interfacial seal is not removed, NASA recommends a bakeout process. Table 1 demonstrates that a simple oven bake is sufficient to reduce volatile matter. The choice is up to the customer. Whatever level of processing, the Glenair mod 429 codes make ordering easy.

Outgassing At-a-Glance

1 Fluorosilicone Interfacial Seals exceed NASA outgassing limits.

2 NASA recommends removing the seal or performing a

bakeout.

3 An inexpensive oven bakeout has better results than the more

costly thermal vacuum outgassing.

4 Glenair Mod 429 codes provide an easy ordering solution,

whatever the outgassing option.

Rev. 06.24.19



Micr

o-D

Spec

ial A

pps a

nd

MOD

s

K

2 screening : What level of screening is required?

What is NASA screening?NASA specification EEE-INST-002 (see figure 2) provides instructions on selecting, screening and qualifying parts for use on NASA GSFC space flight projects. Table 2C in the NASA spec contains specific inspection instructions for MIL-DTL-83513 connectors. These screening requirements exceed the standard mil spec inspection levels.

What screening level is required?NASA defines three levels of screening: level 1 for highest reliability, level 2 for high reliability, and level 3 for standard reliability. Level 3 equates to standard M83513 Group A and B lot acceptance testing, and levels 1 and 2 call for additional testing.

Why does Glenair perform extra screening tests?Glenair has test procedures that go beyond the letter of the NASA spec. Meeting NASA requirements means not only inspecting per EEE-INST-002, but also building parts in accordance with NASA Technical Standard NASA-STD-8739.4 “Crimping, Interconnecting Cables, Harnesses, and Wiring”. Glenair fully meets these requirements and has obtained NASA certification. Our extra inspection steps reflect the fact that pre-wired connectors not only require best practices on the assembly floor, but also require thorough final electrical and mechanical testing.

What about qualification requirements?Qualification is not required if the manufacturer has performed qualification testing per MIL-DTL-83513. Qualification by similarity is usually invoked for those Micro-D’s not specifically covered by the mil spec.

Screening Levels for Space Grade Applications

Due to the dynamic nature of this document, users are advised to check the http://nepp.nasa.gov website prior to every usage to obtain the latest document revision.

1.0 PURPOSE

The purpose of this document is to establish baseline criteria for selection, screening, qualification, and derating of EEE parts for use on NASA GSFC space flight projects. This document shall provide a mechanism to assure that appropriate parts are used in the fabrication of space hardware that will meet mission reliability objectives within budget constraints.

2.0 SCOPE

This document provides instructions for meeting three reliability levels of EEE parts requirements (see 6.0) based on mission needs. The terms “grade” and “level” are considered synonymous; i.e., a grade 1 part is consistent with reliability level 1. Levels of part reliability confidence decrease by reliability level, with level 1 being the highest reliability and level 3 the lowest. A reliability level 1 part has the highest level of manufacturing control and testing per military or DSCC specifications. Level 2 parts have reduced manufacturing control and testing. Level 3 Parts have no guaranteed reliability controls in the manufacturing process and no standardized testing requirements. The reliability of level 3 parts can vary significantly with each manufacturer, part type and LDC due to unreported and frequent changes in design, construction and materials.

GSFC projects and contractors shall incorporate this guideline into their Project EEE Parts Program.

3.0 DEFINITIONS

Screening. Screening tests are intended to remove nonconforming parts (parts with random defects that are likely to result in early failures, known as infant mortality) from an otherwise acceptable lot and thus increase confidence in the reliability of the parts selected for use.

Figure 1: Excerpt from NASA EEE-INST-002

Table 2: NASA Screening Requirements

Inspection/ TestNASA Level

1

NASA Level

2

Glenair Level 1(Mod 429B)

Glenair Level 2(Mod 429)

Visual Inspection 100% 100% 100% (10X) 100%

Mechanical 2 pcs. 2 pcs. 100% 2 pcs.

Voltage (DWV) 100% 2 pcs. 100% 100%

Insulation Resistance

2 pcs. 2 pcs. 100% 100%

Low Level Contact Resistance

2 pcs. 2 pcs.2 pieces

(100% Read and Record)

2 pieces(100% Read and

Record)

Contact Separation Force (pins only)

N/A N/A2 pieces

(100% Read and Record)

N/A

Mating Force 2 pcs. N/A 2 pcs. N/A

Contact/Wire Retention

N/A N/A 2 pcs. N/A

Solderability/Resistance to

Soldering Heat2 pcs. N/A 2 pcs. N/A

Notes: 1. NASA screening requirements from Table 2C of EEE-INST-002.

Rev. 06.24.19



Micro-D

Special Apps and M

ODs

K

3 Magnetic permeability : Are nonmagnetic connectors

required?

Spacecraft designers generally avoid the use of ferromagnetic materials, which can become magnetized and can interfere with sensitive instruments. Micro-D connectors do not contain ferromagnetic materials, so magnetic permeability is not a concern. MIL-DTL-83513 requires a maximum permeability of 2 mu. Glenair hermetic Micro-D connectors are made from Kovar® alloy, a highly magnetic material. The stainless steel e-rings commonly used for Micro-D jackscrew attachment also exceed the 2 mu requirement.

4 Cryogenic exposure : Are Micro-D connectors suitable for

-200° C. ?

Micro-D connectors are rated to -55° C. Glenair has not performed testing below this temperature. EEE-INST-002 states “...experience has proven it is possible for (non-certified) connector types to be used successfully at cryogenic temperatures. It is recommended that connector samples should be subjected to five cycles of cryogenic temperature...(followed by examination for cracks and DWV)”.

5 Materials : Micro-D connectors offer a variety

of materials and plating finishes. Which ones are recommended for space flight?

NASA recommends electroless nickel plated connector shells and crosslinked high strength ETFE (Tefzel®) wire. Cadmium plating is prohibited because it sublimates in a vacuum environment. Gold plating is acceptable but rarely used on Micro-D connector shells. NASA recommends electroless nickel plated connector shells and crosslinked high

Micro-D Connectors and Pre-wired Assembliesfor Space Grade Applications

strength ETFE (Tefzel®) wire. Cadmium plating is prohibited because it sublimates in a vacuum environment. Gold plating is acceptable but rarely used on Micro-D connector shells.

6 Wire Corrosion : M22759/33 irradiated Tefzel® wire is

preferred for space applications. What about corrosion problems caused by this wire?

Does M22759/33 wire have an outgassing problem?Irradiated Tefzel® wire is known to cause tarnishing and corrosion of metal parts in close proximity, usually in sealed bags. Both MIL-DTL-83513 and NASA EEE-INST-002 contain cautionary notes regarding this problem. Wire manufacturers have not been able to eliminate this problem, which might be caused by the insulation extrusion process. This corrosion problem is referred to as “wire outgassing”, which has led to confusion over the term outgassing. This problem has nothing to do with the ability of the wire to meet the TML and CVCM outgassing requirements of ASTM E595. M22759/33 irradiated Tefzel wire continues to be the wire of choice for spacecraft. This wire complies with outgassing requirements.

The corrosion problemMicro-D connectors supplied as pre-wired assemblies should not be stored in sealed bags for extended periods. NASA recommends that parts be inspected for shell discoloration (“a dull “gun metal” appearance) and contact corrosion (“a flat black appearance”). Connectors with corroded contacts should be scrapped.

New Unit Pack MinimizesCorrosionGlenair has adopted a new packaging standard to protect the connector from

Figure 2Fluoropolymer-wrapped

Connector and Perforated Bag

tarnishing or corrosion. Figure 2 shows Glenair’s standard packaging for metal shell connectors supplied with M22759/33 wire. The connector is wrapped in Fluoropolymer tape and placed in a ventilated sulpher-free paper envelope.

“Users are advised that some

ETFE insulations are known

to outgas trace amounts of

corrosive fluorine over time.

When this wire is used with

nickel coated metal shell

connectors are stored in

sealed plastic or ESD bags,

trapped fluorine can attack

exposed metal shells and

contacts.”

Excerpt from Note 9, Table 2, NASA EEE-INST-002

Rev. 06.24.19



save time and cost with modification codes for space grade … · 2019-06-27 · micro-d special...

Documents